By Garth Calitz

The Z-50L is a cantilever low-wing single-engine monoplane featuring a fixed tailwheel undercarriage. In contrast to the Zlín Z 26 series it succeeded, the Z-50 is constructed entirely of metal, with maneuvering load limits of +9.0 and -6.0 g’s. It does not have landing flaps; instead, two-section ailerons span the full wingspan, offering an exceptional roll rate.

The designers ensured ample trimming options: automatic trim tabs are present on the inboard aileron sections, one of the elevators, and the fabric-covered rudder. One aileron includes a ground-adjustable trim tab, while the elevator features a trim tab that can be adjusted during flight.

The standard fuel capacity can be increased with wingtip auxiliary tanks for ferry flights. The bubble canopy provides excellent visibility and can be jettisoned mid-flight if necessary.

In late 1973, a design team led by renowned Czech designer Jan Mikula embarked on developing a new single-seat aerobatic airplane. During the design process, computer optimization was utilized to achieve the desired aerodynamic characteristics. The main objective was to determine the optimal engine and propeller combination for the aircraft. The designers chose the Lycoming AIO-540 D4B5 horizontally-opposed six-cylinder piston engine, rated at 260 hp, paired with a three-blade Hoffmann constant speed propeller. On July 18, 1975, less than two years later, the prototype Zlín Z-50L (with "L" denoting its Lycoming engine), registered as OK-070, made its maiden flight in the Czechoslovakian sky, and the initial flights were very successful.

The Zlín Z 50 first appeared in competition at the 1976 World Aerobatic Championships, piloted by both the Czechoslovak and Polish teams. A Czechoslovak Z-50 secured third place, following two Soviet-piloted Yakovlev Yak-50s, while the Czechoslovak team achieved second place in the team category. In the 1978 championships, the Zlín saw greater success, with Czech-piloted Z 50s taking first and third in the individual competition, and a German-piloted Zlín finishing fourth, leading the Czechoslovak team to victory in the team competition. Zlín Z-50s achieved fourth place in the 1980 championship and third place in the 1982 competition.

The Zlin Z-50LS, equipped with a more powerful 300 HP Lycoming AEIO-540 L1B5D engine, was first piloted by Zdenek Polasek on 29 July 1981. This enhanced engine improved vertical maneuvers. The Zlin Z-50LS is capable of flying at a gross weight of 760 kg in the aerobatic category (+8g to –6g). In the early 1980s, many Z-50L and LA models were upgraded to the Z-50LS standard.

A Z-50LS secured victory in the World Aerobatic Championships in 1984 and 1986, but the introduction of the Sukhoi Su-26 in 1986 eventually pushed the Zlin out of top-tier competition.

The Zlín Z-50M, affectionately called the “Baby Fifty,” was introduced as a successor to the Zlin 26, equipped with an Avia M-137AZ engine generating 180 HP. The Z-50M features limited maneuvering load factors of +7 and -5.5. Only five Z-50M aircraft were produced.

In April 1990, a Z-50LS underwent wing modifications to assess improvements in maneuverability. This aircraft was designated as the Z-50LE (Experimental). It remained a prototype and is currently located at the Czech air school in Moravska Trebova.

The final iteration of the Zlin 50 is the Z-50LX, which made its maiden flight in 1991 with Zlin's chief pilot, Vladimir Peroutka, at the controls. This model was equipped with extra fuel tanks in the wings and a durable smoke system for airshow performances. Its production was mainly driven by show pilot Victor Norman. Between 1992 and 1995, seven Z-50LX units were constructed, with four being utilized by the Red Bull Flying Bulls Aerobatics Team under the leadership of Radka Máchová.

Variants of the Zlin 50 include:

Z-50L

First production variant with a Lycoming AEIO-540-D4B5 engine, certified in 1977, conversion to 50LA and 50LS variants, 25 built. Serial numbers 0001-0025

Z-50LA

Variant certified in 1980, five built and 18 conversions from Z-50L.

Z-50LS

Variant certified in 1982 with a Lycoming AEIO-540-L1B5D engine, 34 built and 18 converted from Z-50, one aircraft was rebuilt as a Z-50M and two as Z-50LX.

Z-50LX

Variant certified in 1991 with a Lycoming AEIO-540-L1B5D engine, nine built, with two converted from Z-50LS, two were rebuilt as Z-50LS.

Z-50M

Variant certified in 1989 with a LOM M 137 AZ engine, six built and one conversion.

General characteristics of the Zlin 50 LS

Crew: 1

Length: 6.62 m (21 ft 8¾ in)

Wingspan: 8.58 m (28 ft 1¾)

Height: 1.86 m (6 ft 1¼ in)

Wing area: 12.5 m² (134.55 ft²)

Airfoil: NACA 0018 at root, NACA 0012 at tip

Aspect ratio: 5.89:1

Empty weight: 570 kg (1,257 lb)

Max. takeoff weight: 720 kg (1,587 lb)

Powerplant: 1 × Lycoming AEIO-540-L1B5D air-cooled flat-six engine, 300 hp

Performance

Never exceed speed: 181.5 knots, 209 mph

Maximum speed: 158 knots, 182 mph at 1,640 ft

Cruise speed: 129 kt, 149 mph economy cruise at 1,640 ft

Stall speed: 53 knots, 61 mph

Range: 640 km (345 nmi, 397 mi) with max fuel, including tip tanks

Service ceiling: 19,675 ft

Rate of climb: 2,360 ft/min

Wing loading: 57.6 kg/m² (11.8 lb/ft²)

Power/mass: 3.71 kg/kW (6.10 lb/hp)

Many of these amazing machines made their way to South Africa over the years and are still used in aerobatic competitions today, Werner Nel took to the air at Kitty Hawk airfield on Sunday 1 October 2017 in his rebuilt Zlin 50 LS under the watchful eye of Chris Joubert, Chris also owns a Zlin 50 LS and they are both expected to take part in the upcoming competition aerobatics season this coming year.